How ecological surveys provide invaluable data for Wildlife Trust in Cambridgeshire

Caroline Fitton, of the Wildlife Trust in Cambridgeshire, explains the importance of gathering data on our nature reserves.

The early summer months are peak season for conducting ecological surveys – the busiest time of year for the Wildlife Trust in Cambridgeshire’s monitoring and reserves staff along with volunteers, out with clipboards and measuring kit across the county.

The gathering of invaluable data informs the management of nature reserves as well as bringing a picture of species faring well or those in decline; surveys take place of all flora and fauna – mammals, birds, reptiles, insects as well as plant species from orchids to grassland specialists.

Bird species records are valuable in themselves, forming part of datasets which can be compared over time, looking for trends at any given site, also contributing records to national monitoring schemes. Some trust reserves which have local or national conservation designations (eg Local Wildlife Site, Site of Special Scientific Interest) are selected because of important bird populations of particular species, so at these sites those specific species can be studied.

Surveys involve six early morning visits between March and June, walking a fixed transect and recording on a map all species seen or heard. The maps are then analysed to estimate the number of territories held by each species, to give an indication of breeding.

To look at the data, birds are split into categories, which can include species groups or groups based on nesting choices, which can bring more information about the site. For example, many woodland warbler species like to nest in low, dense scrub, so high numbers of these species would indicate there is good understorey structure.

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High numbers of cavity nesters (tits and woodpeckers) show that standing deadwood features are frequent on a site.

Senior monitoring and research officer Siân Williams explains: “We currently conduct breeding bird surveys at 23 nature reserves, many of which have more than one transect. Most of these, and the data analysis, is done by volunteers, so a big thank you to our volunteers!”

Thorpe Wood near Peterborough has had an ongoing transect for more than 10 years: on average 28 different bird species are recorded, including an average of 15 breeding species. This has remained fairly stable over the years – eight of the species recorded breeding are red or amber listed/birds of conservation concern.

On recent a breeding bird survey at the wood, ecological consultant Sarah Lambert observed a family of treecreepers, Certhia familiaris, feeding their young, as her photographs show.

Sarah says: “It certainly felt chilly in Thorpe Wood just before 6am, but the birds were singing and after recording the transect I was delighted to spend some time with the treecreeper family, who were busy feeding their offspring, responding to their incessant high-pitched calls. This is the second time we’ve had proven treecreeper breeding.

“Not all birds are doing so well this year; nuthatch are absent for the first time for several years and jackdaw numbers seem to have plummeted.”

Similar in size to a wren with a long downward curved bill, once seen, a treecreeper is unmistakable.

Usually active during the day, they creep up trees in an upward spiral, exploring bark and crevices, using their long, sharp beaks to pick out insects such as spiders and earwigs. Once at the top they fly down to the base of another tree and repeat their upward climb – unlike the nuthatch, they can’t climb down head first. Their long, curved toes help them cling to the bark, and their stiff tail feathers mean that they can push against the tree for extra support.

Breeding begins in April with nests constructed of spiders’ webs, grass, moss and feathers and wedged into a crevice, usually between a tree and loose bark. Clutches are of five to six eggs; the chicks fledge at around 15 days old, but will return to the nesting site for a few days to be fed by their parents.

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When it comes to reptiles some require that handlers are Natural England licensed such as great crested newts: in-house licensed handler reserves officer Chantelle Warriner helped out on a recent survey at Grafham Water.

Surrounded by grassland three ponds in close proximity provide the ideal habitat for all different life stages for this newt; the ponds were checked using torch light and bottle traps – this is done every few years to ensure that the thriving newt population is in good health, as well as to inform on future management.

On this survey 28 were observed – 12 male, 15 female and one juvenile, with eggs found in all ponds, along with 47 smooth newts.

The amphibious great crested newt actually spends most of its life on land, so protecting the terrestrial habitat is just as important as conserving water sources. They like hedgerows and boggy grassland where they can hunt for invertebrates in summer and autumn, and safe hidden spaces to lie dormant during the winter. Their presence is a great indicator of the health of a water source.

For more, visit wildlifebcn.org/nature-reserves/thorpe-wood and wildlifebcn.org/grafham-water.

You can support the trust’s invaluable survey work at wildlifebcn.org/support-us.